A chronic problem for threaded fasteners is the tendency of the connection to loosen under vibration. One approach to a locking fastener for the aerospace industry has been to provide slots at one end of a nut and crimp the nut inwardly at that location so as to form an interference when a bolt enters. The bolt then deflects the slotted part of the nut outwardly as it enters, and these sections of the nut act as resiliently deflected beams which bear inwardly against the surface of the bolt to create a locking effect. Another type of locking nut has an end portion that is uninterrupted but has a relatively thin wall which is deflected to an out-of-round configuration. Entrance of the bolt into the nut then tends to deflect the thin walled part back toward a circular shape so that this portion of the nut exerts a resilient force against the bolt to prevent loosening under vibration.
Locking fasteners of these types have certain disadvantages. One is that the amount of inward deflection of the end of the nut cannot be controlled with precision. When an end part of the nut is crimped inwardly, some spring back will occur so that the exact configuration of the nut end cannot be established. In addition, nuts of this type can be reused only a limited number of times, because when deflected toward a cylindrical shape a number of times they tend to assume a cylindrical shape and lose their ability to lock against the thread of the bolt. Furthermore, nuts of this type may cause galling of the threads when the bolt and nut are mated.
Consequently, there has existed a need for an effective and trouble free locking nut.